NH woman faces cover-up charge in killing of Lizzi Marriott

A 19-year-old Portsmouth, N.H., woman has been arrested for allegedly helping cover up the killing in October of Elizabeth “Lizzi” Marriott of Westboro.

Kathryn “Kat” McDonough was arrested Monday and charged with hindering apprehension or prosecution and conspiracy to commit hindering apprehension or prosecution. At the time of Ms. Marriott's disappearance, Ms. McDonough was the girlfriend of Seth Mazzaglia, the man who has been charged with killing Ms. Marriott.

Robert E. Marriott, father of Ms. Marriott, received word of the second arrest in his daughter's murder case shortly after 1 p.m. Monday.

“I look at it as a positive sign that the police investigation is moving forward,” Mr. Marriott said.

Mr. Marriott said he did not know any details about any connection or relationship between Ms. McDonough and his daughter.

But Mr. Marriott did say he heard Ms. McDonough's name months ago in connection with the investigation.

“I never heard of her name before Lizzi went missing,” Mr. Marriott said.

Mr. Mazzaglia, 29, of Dover, N.H., has been charged with second-degree murder in connection with the death of Ms. Marriott, a marine biology student in her first semester at the University of New Hampshire in Durham. She was a 2011 Westboro High School graduate and former junior prom queen.

New Hampshire Assistant Attorney General Peter Hinckley said the charges against Ms. McDonough allege that during an interview with police, she gave a false alibi about her and Mr. Mazzaglia's whereabouts on the night of Oct. 9. In addition, Mr. Hinckley said, Ms. McDonough gave false statements regarding her “lack of interaction” with Ms. Marriott.

Mr. Hinckley said Ms. McDonough was arrested at her place of work without incident. Ms. McDonough's bail was set at $50,000, but Mr. Hinckley said that amount will likely change when she is arraigned Wednesday in Derry District Court in New Hampshire. Ms. McDonough is still in custody, Mr. Hinckley said.

Mr. Mazzaglia was arraigned Oct. 15 on the second-degree murder charge. He graduated from UNH six years ago with a bachelor's degree in theater and has worked in various theater jobs and as a martial arts instructor.

Mr. Mazzaglia is being held without bail at the Stafford County House of Correction in Dover.

A 2012 honors graduate of Portsmouth High School, Ms. McDonough is an avid “Harry Potter” fan who dressed as “Nymphadora Tonks,” a character from the popular series of J.K. Rowling's novels, and waited hours in line for the midnight showing of “Harry Potter and the Deathly Hallows: Part 2” last year in Newington.

In 2011, Mr. Mazzaglia and Ms. McDonough starred in the Players' Ring production of Lawrence Hennessey's “Last Rites.” Players' Ring Theatre is in Portsmouth.

New Hampshire officials have searched unsuccessfully for Ms. Marriott's body in the waters off Peirce Island in Portsmouth.